When I switch the heating on the boiler fan comes on, the heating cirulation pump comes on but the boiler does not fire up. There is no pilot or flame and the third light on the boiler does not come on. Any ideas? It was working 12 hours earlier.
Check the voltage going to the gas valve, if none present the your air pressure switch could be faulty. Check the two pipes coming from the fan to the pressure switch are not cracked, if so change them.